Question

С железнодорожной станции в 12 ч вышел скорый поезд со скоростью 70 км / ч . На 3 ч раньше с этой же станции был отправлен в том же направлении товарный поезд . В 16 ч скорый поезд догнал товарный .найдите скорость товарного поезда .

Answer 1

16-12=4 часа - время скорого в пути

4+3=7 часов - время товарного в пути

4*70=280км - путь

280/7=40км/ч - скорость товарного

Answer 2

16-12=4 часа до встречи

70*4=280 км путь скорого поезда

4+3=7 часов потратил на это расстояние товарный

280/7=40 км/ч скорость товарного

Answer 3

Problem Analysis

We are given that a fast train left a railway station at 12:00 PM with a speed of 70 km/h. Three hours earlier, a freight train was sent in the same direction from the same station. We need to find the speed of the freight train.

Solution

To find the speed of the freight train, we can use the concept of relative speed. The relative speed of the fast train with respect to the freight train is the difference between their speeds. Since the fast train catches up to the freight train at 4:00 PM, we can calculate the time it took for the fast train to catch up to the freight train. Then, we can use the formula:

Relative Speed = Distance / Time

Let's calculate the time it took for the fast train to catch up to the freight train.

Calculation

The fast train catches up to the freight train at 4:00 PM, which is 4 hours after it left the station. Therefore, the time it took for the fast train to catch up to the freight train is 4 hours.

Now, let's calculate the relative speed of the fast train with respect to the freight train.

Relative Speed = Distance / Time

The distance traveled by the fast train in 4 hours can be calculated using the formula:

Distance = Speed * Time

Substituting the values, we have:

Distance = 70 km/h * 4 h = 280 km

Now, let's calculate the speed of the freight train using the formula:

Relative Speed = Distance / Time

Substituting the values, we have:

Relative Speed = Speed of Fast Train - Speed of Freight Train

280 km / 4 h = 70 km/h - Speed of Freight Train

Simplifying the equation, we have:

Speed of Freight Train = 70 km/h - 280 km / 4 h

Calculating the value, we have:

Speed of Freight Train = 70 km/h - 70 km/h = 0 km/h

Therefore, the speed of the freight train is 0 km/h.

Answer

The speed of the freight train is 0 km/h.